As it was reported last week, Amazon's France-based website has begun to take pre-orders for Grand Theft Auto 5 on the PC. The game has, thus far, only been confirmed for release on the Xbox 360 and PlayStation 3. Rockstar Games has not made any formal announcements about the potential release of the game on the Windows PC, but they've also declined to deny that it'll ever show up on the platform.
Previously, both GTA IV and LA Noire were released on the PC over half a year after they came out on the console. It's highly possible that the same will happen for GTA V on the PC. As Rockstar still needs time to complete their development of the game on the console, it's unlikely that they'd diversify their attention towards developing a PC version of the game at the very same time, especially when they're so close to missing the game's release window of Spring 2013.
The good news for PC gamers is that Amazon appears to be taking a PC version for granted, and has since put up the listings for GTA V on both its Amazon UK and Amazon Germany websites, with Take 2 Interactive listed as its publisher. Given the close relationship retailers have with publishers, it's somewhat unlikely that they'd post up the listings on a whim.
It's far too soon to consider this a confirmation of the game's release on the Windows PC, but things are certainly looking up.